Method of assembling a sensing device having a double clinch seal

ABSTRACT

A device for sensing pressure and temperature in a fluid environment includes a cover defining an interior. A thermistor tube is positioned at least partially within the interior, the thermistor tube extending substantially along a longitudinal axis. A port body is also positioned at least partially within the interior, the port body forming a channel which extends along the longitudinal axis for receiving a fluid from the fluid environment. A diaphragm is affixed within the port body. The diaphragm has a first surface exposed to the fluid within the channel and a second surface sealed from the channel.

FIELD OF THE INVENTION

The subject disclosure relates to sensors, and more particularly to improved devices for sensing both pressure and temperature.

BACKGROUND OF THE INVENTION

Pressure and temperature sensing technology is being incorporated in an increasing number of applications in a variety of different environments. For example, in the automotive industry, pressure and/or temperature sensors are now incorporated into fuel systems, braking systems, and vehicle stability systems, among many others. As the use of sensing technology becomes more widespread, there is an increasing need for accurate and affordable devices for measuring pressure and temperature. Further, as technology continues to evolve, it is desirable for sensors which are configured to occupy as little space as possible while still being reliable.

SUMMARY OF THE INVENTION

The subject technology overcomes the drawbacks of the prior art by providing a pressure and temperature sensor integrated into a single device which is accurate, affordable, and occupies a limited amount of space.

In at least some embodiments, the subject technology relates to a device for sensing pressure and temperature in a fluid environment. The device has a cover defining an interior, the cover including, within the interior, an annular flange. A port body has an outer annular ring which couples with the annular flange to form a double clinch seal. The double clinch seal hermetically seals the port body to the cover. The port body further has interior walls which surround a thermistor tube to form a channel for receiving a fluid from the fluid environment, the channel extending substantially parallel to a longitudinal axis. At least one diaphragm is affixed within the port body along a plane substantially parallel to the longitudinal axis. Each diaphragm has at least one pressure sensing element coupled to a surface distal to the channel. The device further includes an electronics module assembly with a first end and a second end. The first end is positioned above the thermistor tube along the longitudinal axis and has a plurality of electronic components. The second end is positioned within the thermistor tube and has a plurality of thermistor elements electrically connected to the electronic components. Each thermistor element is calibrated to sense temperature within a different specified range. Each pressure sensing element is calibrated to sense pressure within a different specified range and offset from the electronics module assembly.

In at least some embodiments the subject technology relates to a device for sensing pressure and temperature in a fluid environment with a cover defining an interior. A thermistor tube is at least partially within the interior, the thermistor tube extending substantially along the longitudinal axis. A port body is positioned at least partially within the interior, the port body forming a channel which extends along the longitudinal axis for receiving a fluid from the fluid environment. A first diaphragm is affixed within the port body. The first diaphragm has a first surface exposed to the fluid within the channel and a second surface sealed from the channel. In some embodiments the thermistor tube is offset from the port body and the port body is sealed to the cover via a double clinch seal. In other embodiments the port body has interior walls which surround the thermistor tube with respect to the longitudinal axis and the channel is formed between the port body and the thermistor tube. The first diaphragm then forms a plane substantially parallel to the longitudinal axis.

In some embodiments the device includes a first pressure sensing element coupled to the second surface of the first diaphragm. In some cases the device includes a second pressure sensing element coupled to the second surface of the first diaphragm. In other embodiments, a second diaphragm is affixed within the port body and extends substantially parallel to the longitudinal axis. The second diaphragm can have a first surface exposed to the fluid within the channel and a second surface sealed from channel. A second pressure sensing element can be coupled to the second surface of the second diaphragm. In some embodiments, the pressure sensing elements are each calibrated to sense pressure within a different specified range. The thermistor tube can also include a load bearing flange extending across the channel to contact an upper portion of the port body.

In some embodiments, the device also includes an electronics module assembly extending substantially along the longitudinal axis. The electronics module assembly has a lower end positioned within the thermistor tube and coupled to a thermistor element. The electronics module assembly can include at least one additional lower thermistor element coupled to the lower end of the electronics module assembly within the thermistor tube. In some cases, each additional lower thermistor element is calibrated to sense temperature within a different specified range. The electronics module assembly can also include an upper end positioned above the thermistor tube along the longitudinal axis, the upper end having a plurality of electronic components.

In some embodiments the subject technology relates to a device for sensing pressure and temperature in a fluid environment. The device includes a cover defining an interior which has an annular flange within the interior. A port body with an outer annular ring is positioned within the interior. The outer annular ring couples with the annular flange to form a mechanical seal, sealing the port body to the cover. In at least one embodiment the mechanical seal is a double clinch seal. A thermistor tube can be positioned within the interior and have an open top portion and a closed bottom portion. A channel can be formed between the thermistor tube and the cover for receiving a fluid from the fluid environment.

In some embodiments, the device includes an electronics module assembly. The electronics module assembly has a lower end positioned within the thermistor tube and having a plurality of lower electronic components. The electronics module assembly also has a central portion extending through the open top portion of the thermistor tube. Finally, a top portion of the electronics module assembly is positioned above the thermistor tube and has a plurality of upper electronic components. The lower end of the electronics module assembly can have a plurality of thermistor elements. In some embodiments, the lower end electronic components include signal conditioning electronics. The device can include a diaphragm affixed within the port body and forming a plane substantially parallel to the channel. The diaphragm can be configured to flex in response to a pressure from the fluid. Further, a pressure sensing element can be coupled to a surface of the diaphragm for sensing pressure in the fluid environment based on the flexure of the diaphragm.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those having ordinary skill in the art to which the disclosed system pertains will more readily understand how to make and use the same, reference may be had to the following drawings.

FIG. 1 is a perspective view of an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 2 is a cross sectional perspective view of an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 3 is a cross sectional front view of an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 4 is a perspective view of the interior of a port body in accordance with the subject technology.

FIG. 5 is a perspective view of an electronics module assembly in accordance with the subject technology.

FIGS. 6A-6E show a method of assembling an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 7 is a cross sectional view of an integrated pressure and temperature sensor using a load flange in accordance with the subject technology.

FIG. 8A is a perspective view of an integrated pressure and temperature sensor in accordance with the subject technology showing a stress profile.

FIG. 8B is a perspective view of an embodiment of an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 9A is a perspective view of an integrated pressure and temperature sensor in accordance with the subject technology showing a temperature profile.

FIG. 9B is a perspective view of an embodiment of an integrated pressure and temperature sensor in accordance with the subject technology.

FIG. 10 is a cross sectional view of another embodiment of an integrated pressure and temperature sensor in accordance with the subject technology.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The subject technology overcomes many of the prior art problems associated with sensors. The advantages, and other features of the systems and methods disclosed herein, will become more readily apparent to those having ordinary skill in the art from the following detailed description of certain preferred embodiments taken in conjunction with the drawings which set forth representative embodiments of the present invention Like reference numerals are used herein to denote like parts.

Referring now to FIG. 1, an integrated pressure and temperature sensing device in accordance with the subject technology is shown generally at 100. The device 100 contains components for sensing a pressure within a fluid environment 102, as discussed more fully herein. The device 100 has a housing 104 and cover 106 which detachably join together to enclose the inner components. The cover 106 has a threaded bottom section 10 which allows it to be securely fastened within the fluid environment 102. The housing 104 contains an upper outlet 110 which can receive a connector to put the inner components in electrical connection with external devices.

Referring now to FIGS. 2-3, a cross sectional view of an integrated pressure and temperature sensor is shown generally at 200. As shown, the cover 206 securely holds the device 200 within the fluid environment 208. A channel 226 for receiving a fluid 228 from the fluid environment 202 is defined between a thermistor tube 224, a port body 216, and the cover 206. In general, the port body 216 includes sensing elements 230 for sensing pressure while the thermistor tube 224 contains thermistor elements 232 for sensing temperature. The channel 226 extends along the longitudinal axis “a”, allowing for the receipt of fluid laterally with respect to the flow “f” of the fluid environment 202.

The cover 206 defines an interior within which it has an inner annular flange 212. The inner annular flange 212 couples with an outer annular ring 214 of a port body 216 to form a mechanical seal 218, thereby sealing the cover 206 to the port body 214. In the embodiment shown, the mechanical seal 218 is a double crimp seal. The seal 218 prevents fluid 228 from entering a cavity 220 defined by the housing 204 and the cover 206 within which an electronics module assembly 222 is seated. The electronics module assembly 222 is also affixed to the housing 206 and the port body 216 by a support member 248 for stability.

Still referring to FIGS. 2-3, in the embodiment shown, thermistor elements 232 track temperature as the fluid 228 in the channel 226 contacts the thermistor tube 224. While only one thermistor element 232 is shown in the present example, it should be noted that multiple thermistor elements 232 can be used near different locations within the thermistor tube 224 to track temperature within different ranges, as discussed more fully herein. Generally the thermistor elements 232 are positioned somewhere along the lower portion 242 electronics module assembly 222 which is contained within the thermistor tube 224. The thermistor elements 232 are in electrical communication with the electrical components 238 on the upper portion 240 of the electronics module assembly 222. For example, the thermistor elements 232 can be connected to the electrical components 238 by interconnects (not shown herein).

Similarly, but for pressure, two sensing elements 230 are affixed on flexible portion of the port body 216. More particularly, the port body 216 has a sidewall 234 with one or more areas having a lessened width, as compared to the rest of the port body 216. The inner surface of the sidewall 234 is exposed to fluid 228 within the channel 226. This allows one or more areas of the sidewall 234 to flex depending on the pressure in the fluid environment 202. For example, the sidewall 234 may contain multiple thin, flexible areas, acting as individual diaphragms and positioned under each sensing element 230. Alternatively, the entire sidewall 234 may serve as a diaphragm and one or more sensing elements 230 may be positioned at different locations on the sidewall 234. In general, the sensing elements 230 are affixed to outer surfaces of the sidewall 234, or diaphragms, thereby limiting or eliminating physical contact between the sensing elements 230 and the fluid 228 (notably, the terms “sidewall” and “diaphragm” are used interchangeably herein to denote the flexible portion of the port body 216). The sensing elements 230 transmit a signal, via interconnects 236 to electric components 238 on the upper portion 240 of the electronics module assembly 222. The combination of the housing 204, cover 206, and port body 216 keep the sensing elements 230 isolated from the fluid 228 within the channel 226.

In the embodiment shown, the sidewall 234 and the sensing elements 230, are positioned along a plane parallel to the longitudinal axis “a” (and thus, parallel to the channel 226). By positioning the sidewall 234, and thus the sensing elements 230, along a plane parallel to the fluid channel “a”, the sensing elements 230 can be calibrated to correspond with the various magnitudes of pressure felt at different locations of the sidewall 234, as discussed more fully herein. Further, by orienting many the components laterally (i.e. the electronics module assembly 222, the thermistor tube 224, the sidewall 234), along the longitudinal axis “a”, the width of the device 200 is reduced while accuracy is still preserved. Notably, while two sensing elements 230 are shown, various amounts of sensing elements 230 can be used, such as one, three, four, or more, depending on the desired application, as discussed in more detail below.

Referring now to FIG. 4, a bottom perspective view of a port body 216 is shown. Sensing elements 230, shown in phantom, are affixed to the exterior of the sidewall 234. When the port body 216 is incorporated with the rest of the device 200 and used in practice, it is expected that the sidewall 234 will be parallel and adjacent to the fluid channel 226. Therefore the sidewall 234, being parallel to the fluid channel 226, flexes perpendicularly to the flow of fluid 228 through the fluid channel 226. The sensing elements 230 can be anything designed to sense pressure in response to the flexure of a surface. For example the sensing elements 230 can be strain gauges with piezoresistors. As the sidewall 234 flexes, the resistance of the resistors changes in response to the flexure. The resistance of the strain gauge 230 can be measured, for example, by arranging one or more Wheatstone bridges to measure the change in resistance of piezoresistors within each sensing element 230. Based on the resistance of the piezoresistors within the sensing element 230, the flexure of a location of the sidewall 234, and thus the pressure of the fluid in the pressure environment 202, can be determined. The resistance can be communicated to the electronics 238 by the interconnects 236.

Referring now to FIG. 5, an electronics module assembly in accordance with the subject technology as shown generally at 222. A lower thermistor element 232 that is positioned on the bottom portion 242 is in electrical communication with electronics 238 on the top portion 240. In general, the electronics module assembly 222 is incorporated in the device so that the assembly 222 runs along the longitudinal axis “a” with the bottom portion 242 extending through the thermistor tube 224 and the top portion 240 seated above the thermistor tube 224 within the interior of the housing 204 (See FIGS. 2-3). The electronics 238 can include components for storing, interpreting, modifying, and/or transmitting signals from various other components such as the sensing elements 230 and thermistor elements 232. For example, upper electronic components 238 can include a number of bonding pads, signal processing or transmitting equipment, or one or more application specific integrated circuits. A signal from the electronics 238 can be transmitted to external devices by various means such as a wireless signal or a hardwire connection via the upper outlet 210.

Referring now to FIGS. 6A-6E, a method of assembling an integrated pressure and temperature sensor 200 in accordance with the subject technology is shown. Referring to FIG. 6A, the thermistor tube 224 slides into an upper opening of the port body 216. The channel 226 is partially formed between the larger inner diameter “D1” of the port body 216 and the smaller outer diameter “D2” of the thermistor tube 216. The thermistor tube 224 has an upper portion 244 with an outer diameter “D3” that is only slightly smaller than the inner diameter D1 of the port body. Therefore the upper portion of the thermistor tube 224 sits tightly within the port body 216 and the two parts can be welded together near the top for permanent coupling.

Referring now to FIG. 6B, the electronics module assembly 222 is then attached to other components of the device 200. The electronics module assembly 222 is pre-fitted with desired components before it is coupled to the rest of the device 200. For example, the lower portion 242 of the electronics module assembly 222 can include a thermistor element 232 which is electrically coupled to electronic components 238 on the upper portion 240 of the electronics module assembly 222. A thermal paste is then applied within the thermistor tube 224. The electronics module assembly 222 is then slid along the longitudinal axis “a” with the lower end 242 of the electronics module assembly 222 entering the open top portion of thermistor tube 224. The sensing elements 230 can then be connected to the bonding pads (part of electronics 238) on the electronic module assembly 222. Referring now to FIG. 6C, the electronics module assembly is also mechanically attached to a support member 248 which is attached to the housing 206 and/or port body 216 to hold the electronics module assembly 222 in place.

Referring now to FIG. 6D, a seal 218 (i.e. a “double crimp” or “double clinch” as seen in FIGS. 2-3) is formed between the port body 216 and the cover 206. To create this seal 218, the port body 216 is positioned within the interior of the cover 206 with the annular ring 214 of the port body 216 sitting against the annular flange 212 of the cover 206. The cover 206 is formed from a material which is easier to deform than the material of the port body 216. For example, the cover 206 may be aluminum while the port body 216 is steel. A clinching member 250 is then positioned over the top surface of the annular flange 212. As the clinching member 250 is pushed downwards, the upper surface of the annular flange 212 is forced inwards, folding over the upper surface of the annular ring 214. In this way, the annular flange 212 of the cover 206 folds over the annular ring 214 of the port body 216 such that the annular flange 212 is sealed to both the top surface and bottom surface of the annular ring 214 to form a double clinch seal 218. The double clinch seal 218 is a hermetic seal which prevents fluid 228 in the channel 226 from leaking between the port body 216 and cover 206 into the cavity 220.

Referring now to FIG. 6E, the housing 204 is then affixed to the device 200 to completely seal the inner cavity 220. The lower surface of the housing 204 and the upper surface of the cover 206 have alternating teeth 252 which extend around the longitudinal axis “a”. To seal the cover 206 and housing 204, the housing 204 is pressed down the longitudinal axis “a” and the lower surface of the housing 204 forms a crimp with the upper surface of the cover 206. The teeth 252 interlock and the inner cavity 220 between the housing 204 and cover 206 is sealed.

Referring now to FIG. 7, an embodiment of a thermistor tube 624 with a load flange 654 is shown. Unlike the other embodiments shown here, the upper portion of the thermistor tube 624 generally has a diameter “D1” that is substantially the same as the central portion of the thermistor tube. However, slightly below the upper opening of the thermistor tube 624, a wider load flange 654 (having diameter “D2”) is formed. The port body 616 necks inwards, at its upper end, to from a wide inner diameter “D3” to a diameter that is only slight larger than D1, allowing the port body 616 to fit snugly against, and be welded to, the upper portion of the thermistor tube 624. The wider load flange 654 creates a pressure cavity where fluid flowing into the channel 626 applies an upwards force to the load flange 654 of the thermistor tube 624 such that the thermistor tube 624 is pressed more tightly against the port body 616. In this way, the load flange 654 reacts to increased pressure in the fluid channel 626 by sealing the thermistor tube 624 even more tightly to the port body 616.

Referring now to FIGS. 8A and 8B, in some embodiments, the device 200 is designed to include more than one sensing element 230, each being calibrated to sense pressure within a different range. The locations, and calibrated ranges of sensing elements 230, can be based on a stress profile which describes the magnitude of stress on the port body 216 created by the fluid 228. For example, in FIG. 8A, the stress profile shows a first location “a” along the center of the sidewall 234 of the port body 216 that experiences a high degree of stress compared to the rest of the side wall 234. By contrast, areas to the sides of the sidewall 234 “b” show lower stress. Thus, the design results in a configuration where the sidewall 234 can serve the role of multiple diaphragms above areas of varying pressure (or a single diaphragm over areas of varying pressure).

Turning to FIG. 8B, three sensing elements 230 are mounted to the sidewall 234. The first sensing element, 230 a, is mounted at the first location “a” and experiences the most flexure. At location “a”, a very small change in fluid pressure may cause flexure in the sidewall 234 and may affect the resistance of the first sensing element 230 a. As a result, the first sensing element 230 a is calibrated to focus in on a narrower pressure range which relates to expected operating ranges or critical values depending on the application of the fluid 202 being measured. On the other hand, the other sensing elements 230 b, 230 c are mounted at least partially above location “b” which experiences less flexure in response to pressure from the fluid 202. Therefore piezoresistors of the other sensing elements 230 b, 230 c can be positioned about this area of lower flexure (for the present example, this is assumed to be the case). The sensing elements 230 b, 230 c are then calibrated for different ranges of pressure. This can be beneficial to reach a wider pressure range or to provide redundancy in conjunction with other pressure sensing elements 230. It is also possible to use sensing elements 230 b, 230 c at the second location “b” when a user desires to avoid sharp jumps in perceived pressure as a result of small surges which are not representative of actual pressure in the fluid environment 202. Notably, this embodiment is provided only in way of example. In other embodiments, more or fewer sensing elements 230 can be provided. In some cases the sensing elements 230 may be specifically positioned and calibrated depending on a stress profile. In other cases, multiple sensing elements 230 may be calibrated to the same or overlapping ranges simply to provide redundancy and ensure accuracy.

Similarly, referring now to FIGS. 9A-9B, in some embodiments, the device 200 is designed to include more than one thermistor element 232, each thermistor element 232 being calibrated to sense temperature within a different range. The use of multiple thermistor elements 232 in multiple locations is similar to the use of multiple sensing elements 230, as described above, except that the thermistor elements 232 sense temperature. The locations, and calibrated ranges of the thermistor elements 232, can be based on a temperature profile (i.e. FIG. 9A) which describes the temperature felt by various portions of the thermistor tube 224 as a result of the fluid temperature. For example, in the embodiment shown, the thermistor element 232 c is positioned closest to the fluid environment 202 (where temperature is at its highest) and can be calibrated to focus on a specific temperature range in an expected or critical operating range. On the other hand, thermistor element 232 a experiences the least change in temperature and may be calibrated to sense a much wider range, or provide redundancy from a location less susceptible to quick, non-representative changes in temperature felt by the thermistor tube 224. Similarly, in some cases, multiple thermistor elements 232 are provided in similar areas of the temperature profile for accuracy or redundancy.

Referring now to FIG. 10, another embodiment of an integrated pressure and temperature sensing device is shown generally at 1000. Unlike the embodiment shown in FIG. 2, the device 1000 has a port body 1016 that is offset from the thermistor tube 1024. Instead the cover 1006 forms two separate channels 1026, 1060 along the longitudinal axis “a”. The lower portion of the electronics module assembly 1042 is inserted into the first channel 1060, the bottom of which is seated directly within the flow “f” of fluid in the fluid environment 1002. The second channel 1026 is open to the fluid environment 1002 to allow an inflow of fluid. A port body 1016 is affixed within the second channel 1026, and forms a double clinch seal 1018 with the inner walls of the cover 1006. The port body 1016 receives a fluid 1028 through the channel 1026 and directs it to a sidewall 1034. The sidewall 1034 functions as a diaphragm, much like the other sidewalls 234 shown herein, except that the sidewall 1034 runs along a plane perpendicular to the longitudinal axis “a”. A pressure sensing element 1030 senses flexure of the sidewall 1034 and connects to the electronics (not shown) on the upper portion of the electronics module assembly 1022. Similar to the other embodiments, a housing 204 attaches to the cover 1006 to seal the inner cavity 1020. The device 1000 functions similar to other embodiments of the subject technology, except for the differences resulting from the different orientation of the device, as described and shown.

It will be appreciated by those of ordinary skill in the pertinent art that the functions of several elements may, in alternative embodiments, be carried out by fewer elements, or a single element. Similarly, in some embodiments, any functional element may perform fewer, or different, operations than those described with respect to the illustrated embodiment.

Also, functional elements (e.g., electronics, pressure sensing elements, temperature sensing elements, and the like) shown as distinct for purposes of illustration may be incorporated within other functional elements in a particular implementation.

While the subject technology has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the subject technology without departing from the spirit or scope of the subject technology. For example, each claim may depend from any or all claims in a multiple dependent manner even though such has not been originally claimed. 

1-20. (canceled)
 21. A method of assembling a pressure sensing device having a double clinch seal, comprising: providing a cover defining an interior with a pressure sensing element within the interior, the cover having an annular flange within the interior; providing a port body within the interior, the port body having an outer annular ring, a channel being defined by the port body and the cover; forming the double clinch seal between the annular flange and the outer annular ring, the double clinch seal hermetically sealing the cover to the port body around the channel and preventing fluid from the channel from entering the interior.
 22. The method of claim 21, further comprising providing a thermistor tube within the channel, the channel being defined between the cover, the port body, and the thermistor tube, the thermistor tube including a thermistor element within the channel.
 23. The method of claim 21, further comprising pressing a housing against the cover to form a seal and seal an inner cavity around the interior.
 24. The method of claim 23, wherein: a lower surface of the housing and an upper surface of the cover have alternating teeth; and during the step of pressing the housing against the cover, the alternating teeth are interlocked and the housing the alternating teeth crimp to seal the housing and the cover.
 25. The method of claim 21, further comprising affixing the pressure sensing element to a flexible portion of the port body on a surface of the port body opposite the channel.
 26. The method of claim 21, wherein the step of forming a double clinch seal between the annular flange and the outer annular ring includes: positioning the port body within the interior of the cover such that the outer annular ring sits against the annular flange; and forcing a clinching member against a surface of the annular flange to force the annular flange to fold over an upper surface of the outer annular ring such that the annular flange is sealed to both the upper surface of the outer annular ring and a bottom surface of the outer annular ring to form the double clinch seal.
 27. The method of claim 21, wherein the cover is formed from a first material and the port body is formed from a second material, the first material being easier to deform than the second material.
 28. A method of assembling a pressure sensing device having a double clinch seal, comprising: affixing a pressure sensing element to a flexible portion of a port body, the port body having an outer annular ring; sliding a thermistor tube into the port body to form a channel between an inner diameter of inner walls of the port body (D1) and an outer diameter of the thermistor tube (D2), D1 being greater than D2; coupling the thermistor tube and the port body; providing an electronic module assembly including a lower portion with a thermistor element; sliding the lower portion of the electronics module assembly through an open top portion of the thermistor tube such that the thermistor element is within the thermistor tube; electrically connecting the pressure sensing elements to bonding pads on an upper portion of the electronics module assembly; providing a cover, the cover having an interior with an annular flange within the interior; positioning the port body within the interior of the cover such that the outer annular ring sits against the annular flange; and forcing a clinching member against a surface of the annular flange to force the annular flange to fold over an upper surface of the outer annular ring such that the annular flange is sealed to both the upper surface of the outer annular ring and a bottom surface of the outer annular ring to form the double clinch seal.
 29. The method of claim 28, wherein the cover is formed from a first material and the port body is formed from a second material, the first material being easier to deform than the second material.
 30. The method of claim 29, wherein the first material is aluminum and the second material is steel.
 31. The method of claim 28, wherein the thermistor tube includes an upper portion with a diameter (D3), D3 being greater than D2 and slightly smaller than D1, such that the upper portion of the thermistor tube sits tightly within the port body.
 32. The method of claim 28, wherein: the thermistor tube has a substantially uniform diameter of D2 aside from an upper load flange having a diameter greater than D2; and the inner walls of the port body neck inward at an upper end and contact the upper load flange. 